1. Field of the Invention
The present invention relates generally to stick prevention apparatus for protecting medical personnel from injury. More particularly, the present invention relates to tip covering elements having internal conformations which prevent a retracted needle from reemerging therethrough.
2. Description of Prior Art
Medical care of individuals in hospitals, clinics, and other health care facilities often includes the taking of blood samples, intravenous supplying of medication, and the introduction or removal of other fluids via cannulae, needles, or syringes. The present medical environment, in which there exist diseases, for example Acquired Immune Deficiency Syndrome, AIDS, for which there are no cures, and which are transmitted via blood to blood contact, has raised concerns relating to the potential for contaminated "needle sticks".
A wide variety of devices have been provided in the prior art for prevention against accidental contaminated "needle sticks". For example, U.S. Pat. No. 5,215,528 to Purdy et al. (hereinafter Purdy) teaches an assembly for introducing a catheter into a blood vessel, wherein there is provided a tip cover which includes an elastically deforming L-shaped. In an initial disposition, the L-shaped member is positioned in a deformed state with the cannula inserted fully through the cover. Once the cannula is retracted, however, the L-shaped member springs into a position to prevent reemergence of the needle. Manual repositioning of the L-shaped member is necessary to permit the cannula reemerge from the cover.
U.S. Pat. No. 5,127,905 to Lemieux teaches a protection cap, which is similar to the device disclosed by Purdy, as described above. In the Lemieux device an externally mounted rotating L-shaped lever is disposed along the axis of the cover, manual actuation of which by a user once the cannula is retracted prevents the cannula from re-emerging from the cover. Manual retraction of the external L-shaped lever from the path of the cannula permits the cannula to reemerge.
U.S. Pat. No. 4,826,490 to Byrne et al. (hereinafter Byrne) teaches a safety cover and syringe assembly wherein an external cylindrical sleeve, through which the cannula extends, is slidably mounted to a track on the external surface of the syringe. Sliding the external cylindrical sleeve relative to the cannula and the syringe, such that the cannula is fully retracted into the sleeve, causes a locking mechanism to engage between the syringe and the sleeve so that the cannula may not be advanced out of the sleeve without disengagement of the locking elements by a user.
A device, which is similar to the one disclosed in the Byrne reference, is U.S. Pat. No. 4,952,207 which is also to Lemieux. This reference teaches a safety cover for use with a cannula which has a radial notch along the shaft, near the tip. The internal structure of the cover includes a tab which engages the cannula in the notch once the cannula has been retracted. Rotation of the cannula, or the safety cover locks the cannula in position and prevents its reemergence.
As above, however, the Lemieux prevention means may be compromised by intentional, or random, manipulation of the device. While each device includes functional means for preventing "needle sticks" by interfering with the exposure of a cannula once it is retracted into a cover, it is of considerable concern for users of such devices that, if a means for disengaging the retaining element is provided, random forces may expose the contaminated cannula, thus presenting a danger to medical personnel. This concern is especially applicable to the variety of "needle stick" prevention devices which include externally mounted prevention means.
It is, therefore, a principal object of the present invention to provide a needle cover which includes an element or elements which prevent exposure of a contaminated cannula.
It is further an object of the present invention to provide a needle cover which cannot be compromised, whereby the cannula may reemerge therethrough, by application of random environmental forces, or by unintentional manipulation of the device.
It is further an object of the present invention to provide a needle cover which is more reliable in its safety aspects.
Other objects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims.